Simple JavaScript performance tester

jsPerfTest.js

/**
 * This is a simple function that will test the performance of a JavaScript function.
 * It should be noted that it may not be extremely accurate because it depends on your
 * JavaScript runtime's implementation of getTime(). Most of the time, it works great.
 *
 * (For more on performance testing, see http://ejohn.org/blog/accuracy-of-javascript-time/)
 *
 * Here is an example of how to run a performance test:
 *   var result = pfTest(function () { var testAssignment = 0; }, 50);
 *   console.log(result);
 */

var pfTest = function (f, times) {
	times = times || 1000;
	var start = (new Date).getTime();
	for (var i = 0; i < times; i++) f();
	var end = (new Date).getTime();
	return ((end - start) / times) + "ms";
};